Multi-frequency optical unidirectional transmission based on one-way guided mode resonance in an extremely simple dielectric grating

Excellent performance, simple structure and small size are the key measures of an all-optical element. In this paper, an optical diode with multiple operating frequencies is proposed based on an extremely simple dielectric diffraction grating. The optical unidirectional transmission (UDT) is attributed to the guided mode resonance in the grating substrate which occurs in an one-way manner. Compared with the novel UDT phenomenon based on surface plasmon polaritons (SPP) in metallic structures, the performance of this UDT is enhanced greatly: The transmittance can approach almost to 0% and 90% respectively in the two opposite directions. It is achieved at multiple frequencies simultaneously and is not restricted to transverse magnetic (TM) polarized wave. The relationship between the UDT and the reciprocal theorem is also analyzed by taking this kind of UDT for an example. It is found that the reciprocal theorem is still valid in this system and the UDT is obtained by means of channel effect.